1. Field of the Invention
This invention relates to a slitter knife holder for carrying a slitter knife as used in a slitter for slitting a sheet of material such as paper into two or more sheet having a predetermined width.
2. Description of the Prior Art
A conventional slitter knife comprises an upper blade and a lower blade. Generally, the lower blade is fixed in the direction of the axis of rotation of the lower blade, and the upper blade is biased in the direction of the axis of rotation of the upper blade by a spring so that the upper blade may lap over and contact with the lower blade at a pressure. The pressure of contact of the upper blade with the lower blade must be maintained at a predetermined value which is proper to the nature and the thickness of a sheet-like material to be slitted. In the conventional slitter knife wherein the contact pressure of the upper blade with the lower blade is produced by the compressing force of the spring as described above, an operator set a necessary contact pressure by adjusting the degree of compression or displacement of the spring. However, such conventional slitter knife holder does not have means for indicating the contact pressure directly to the operator. Therefore, the operator had to use his head to make such adjustment, and thus it was unavoidable that there was an outstanding difference in such adjustment among individual operators. Moreover, in such a slitter, since the slitter knife wears, it is often necessary to replace the knife by a new one. The operator had to make such an adjustment for each replacement. It was very difficult for the operator to always set the contact pressure to a same proper value for each adjustment by using his head. For these reasons, in conventional slitters, there was a large difference the cantact pressure, thereby resulting in large differences in the life and the cutting quality of the slitter knives.
Therefore, it is an object of this invention to provide a slitter knife holder wherein the contact pressure of the slitter knife can be indicated directly to an operator so as to permit the operator to easily and accurately set a desired contact pressure on the basis of the indication.
It is another object of this invention to provide a slitter knife holder which makes it possible to automatically control the contact-pressure of the upper blade with the lower blade.